电渣重熔技术在中国的应用和发展

中国电渣冶金起步于１９５８年,至今,全国所有特殊钢厂都建立了电渣重熔车间,拥有工业电渣炉８６台,年生产能力１０万ｔ,产品包括估质合金 与超级合金２４３个牌号。     

电渣重熔的冶金质量

从电渣过程的脱硫、脱磷，脱除有害气体，以及非金元素夹杂物的去除和重熔过程中合金元素的变化趋势等角度探讨了提高电渣锭质量的各因素。     

电渣重熔高压锅炉管用钢化学成分变化规律的探讨

通过大量数据的统计及回归分析,探讨了２０Ｇ,１５ＣｒＭｏＧ,１２Ｃｒ１ＭｏＶＧ高压锅炉管用钢电渣重熔前后化学成分的变化规律,并由此推导出２０Ｇ,１５ＣｒＭｏＧ,１２Ｃｒ１ＭｏＶＧ高压锅炉管用钢电渣重熔前后元素含量变化的近似计算公式。用该近似计算公式可确定自耗电极元素含量的控制范围。     

采用高电阻渣电渣重熔高速钢的研究

采用两种渣系进行电渣重熔高速钢的实验，比较了重熔过程的电耗，高电阻率的渣系，由于具有较高的热效率和电效率，可以使电渣重熔电耗降低，在保证钢锭质量的前提下，可以用较小的能量消耗获得较高的生产率，通过低倍及高倍检验研究了钢锭的凝固质量，对实验中重熔锭型其较合理熔速为１４０ｋｇ／ｈ。     

电渣重熔技术的革新

电渣重熔技术是生产非常纯净的特殊钢和合金所采用的生产工艺，这一点已经得到了很好地证明。该技术的近期开发将会在钢工业领域有新的应用。新开发的快速电渣重熔工艺(ESRR)能够以较高的熔化速率重熔小坯料，而新的导电结晶器技术甚至可为非常大的钢锭分别提供温度和熔化速率的控制。没有自耗电极的电渣重熔(ESR)工艺彻底开辟了如像电渣连铸这样的可能性。     

非真空感应炉—电渣重熔冶炼高氮不锈钢的实验研究

采用非真空感应炉-电渣重熔炉进行了高氮不锈钢的冶炼实验,分析了电渣锭成分的均匀性,并对电渣锭的内外部质量进行了检测。采取合适的氮合金化和出钢工艺,较好地控制了钢锭凝固过程中的氮溢出问题,电渣锭成分均匀,内外部质量良好,可以满足用户的质量要求。     

电渣重熔对奥氏体钢低温韧性的影响

测定了77K下22Mn-13Cr-5Ni-0.25N奥氏体钢电渣重熔前后的冲击韧性、氢含量及夹杂物含量,并利用扫描电子显微镜和透射电子显微镜研究了电渣重熔对该钢低温韧性的影响,结果表明：电渣重熔使钢中氢和夹杂物含量显下降,有利于抑制γ→ε转变,减小应力集中,从而提高了该,多的低温韧性。     

降低电渣重熔GCr15钢的氧含量

在420mm／250mm方形结晶器的工业炉上重熔1．2t锭,比较了含高氟的二元渣系、低氟和中氟的五元渣系、重熔气氛（Ar气保护）、自耗电极表面质量、渣中aFeO值和自耗电极含氧量对重熔钢氧含量的影响。结果表明,自耗电极氧含量为5．87×10-6和10×10-6．在氮气气氛、低氟五元渣系下重熔,电渣过程是一个增氧过程,重馆过程中降低渣中aFeO值,可使GCr15钢的氧含量降至15×10-6左右。     

Hydrogen Pick-Up During Electroslag Remelting Process

  The pick up of hydrogen during electroslag remelting process for several slags consisting of CaF2 Al2O3 CaO SiO2 MgO had been investigated. The laboratory scale remelting experiments had been carried out in open air and water free argon atmosphere, and then the influencing factors were analyzed. It had been found that the hydrogen content in steel varied with different slag compositions. The compositions and state of slag had significant effect on the hydrogen level in steel. Partial return slag and premelted slag could avoid the hydrogen pick up especially in the early stages of the process. However, premelted slag was the optimum state to control the hydrogen pick up in steel. Experimental results indicated that water free argon atmosphere was very favorable to the control of hydrogen in steel in the normal remelting period.     

具有发展潜力的电渣冶金技术

为了提高铸锭质量,降低生产成本,电渣冶金涌现出许多新的技术,介绍了几种具有发展潜力的国内外电渣冶金新技术,包括弧渣重熔、洁净钢形核铸造、单极电渣快速重熔、双极电渣连铸、旋转电极重熔技术和液态金属电渣冶金技术。     

电渣重熔与连铸轴承钢中的夹杂物

研究了电渣重熔前后钢中氧及夹杂物的变化,结果表明:用电渣重熔工艺生产轴承钢,虽然氧含量比连铸钢高,但其大颗粒夹杂物数量少,尺寸较小,分布均匀,因此疲劳寿命高.     

电渣重熔工艺对GH4169脱硫的影响

 为进一步降低GH4169中的硫含量,进行了大气下、氩气氛保护及氩气氛保护下向渣池加钙精炼3种工艺条件对脱硫效果影响的电渣重熔试验。结果表明,大气下重熔时脱硫效果明显,硫含量(质量分数,下同)由18×10-6降低到6×10-6,渣中的硫通过气化反应脱除;氩气氛保护不利于电渣重熔工艺的脱硫,硫含量降低到7×10-6后提高到9×10-6,熔渣中的硫不断富集;硫分配比的计算值与实测值的对比研究表明,电渣重熔脱硫热力学条件优越,动力学条件是限制实际脱硫效率进一步提高的主要因素;氩气氛保护下通过向渣池加钙后,熔渣中钙元素能够对合金进行脱硫且脱硫率有较大幅度的提升,合金中硫含量随钙含量的增加而减少,重熔结束时硫含量降至3×10-6。     

Electroslag Remelting Withdrawing Technology for Offshore Jack-up Platform Rack Steel Manufacturing Process

Offshore jack-up platform rack steel must exhibit high strength and toughness as well as excellent welding properties.A high-quality large ingot is a prerequisite for obtaining a high-performance rough part.The electroslag remelting withdrawing(ESRW)technology using a T-shaped mold and bifilar mode was introduced to replace casting technology.Numerical simulation of the ESRW process was performed to determine the distribution of the temperature and velocity fields and to determine the optimum process for producing rack steels.Several A514 Qslab ingots with dimensions of 0.32m×1.40m×4.00 m were produced using ESRW technology in an industrial plant.The industrial test indicated that slab ingots produced by the ESRW method exhibited uniform chemical compositions and compact macrostructures.A 115.4mm thick plate was produced from the rough ingot after 11 rolling passes.Samples were obtained from different positions in the steel plate to test the mechanical performance and examine the microstructure,and the results revealed that the properties of the steel plate satisfied ASTM standards.The ESRW process improved the tensile strength and toughness of the slab ingot,enabling significant improvements in the anisotropy and low temperature toughness,which are critical for the development of rack steel for offshore platforms.     

Mathematical Model for Electroslag Remelting Process

 A mathematical model, including electromagnetic field equation, fluid flow equation, and temperature field equation, was established for the simulation of the electroslag remelting process. The distribution of temperature field was obtained by solving this model. The relationship between the local solidification time and the interdendritic spacing during the ingot solidification process was established, which has been regarded as a criterion for the evaluation of the quality of crystallization. For a crucible of 950 mm in diameter, the local solidification time is more than 1 h at the center of the ingot with the longest interdendritic spacing, whereas it is the shortest at the edge of the ingot according to the calculated results. The model can be used to understand the ESR process and to predict the ingot quality.     

用等离子旋转电极工艺生产高氮钢

为了寻求高效、经济的高氮钢生产工艺,用等离子旋转电极工艺(PREP)生产高氮钢并测试了所生产的几种典型高氮钢的性能。结果表明,氮可显著地提高奥氏体不锈钢1．4301的室温及高温强度;氮可以提高马氏体不锈钢的强度。为保证高氮马氏体不锈钢的淬透性,应根据氮含量适当降低其碳含量或提高铬含量。对于铬含量为17％的马氏体不锈钢1．4122,其碳和氮的总含量不应超过0．65％;当氮含量达到0．24％时,铁素体不锈钢1．4016转变成为马氏体钢,其强度高于碳和氮的总含量与其相当的普通马氏体不锈钢1．4122。     

氮气加压熔炼高氮钢技术的研究进展

在综述氮气加压熔炼高氮钢技术的基础上，指出了大熔池法（BSB）适合于工业化大规模制备高氮钢；并基于国内几十年来电渣冶金技术的丰富经验，提出了采用电弧渣重熔（ASR）和加压电弧渣重熔（ASRP）技术生产高氮钢是目前较为可行的技术方案。     

Segregation of Niobium During Electroslag Remelting Process

 Experiment was carried out after the process parameters were calculated by the model previously established. The relationship between interdendritic spacing and local solidification time (LST) mainly determined by process parameters was exposed. Furthermore, the extent of segregation was studied. The results indicate that LST and interdendritic spacing are the largest and the amount of Laves phase as a result of the niobium segregation is the highest in the center of the ingot, whereas the opposite results are obtained at the edge of ingot. The extent of element segregation and the amount of Laves phase can be reduced when appropriate parameters are used. Therefore, the duration of subsequent homogenization treatments for 718 is shortened and the alloy quality is improved.